Hello! Im having some difficulty with one of my euphorbias and my friend, Akos Kokai, suggested that I email you. My devil’s backbone has been growing this layer of powdery white dust for some time now. At first, it was very little and I thought it might be natural to the plant. But now it’s proliferating and killing off the leaves. Do you know what it might be? I’ve isolated the plant and have tried neem oil and alcohol treatments, but it keeps growing back.
It’s powdery mildew, a fungus. It’s pretty easy to cure, and we have some organic fungus treatments that work well, but these plants are definitely prone to it. We can recommend either of two products we carry: Safergro Mildew Cure or EcoSmart Garden Fungicide.
I recommend using one of these at the first sign of trouble. The Pedilanthus will do better with better air circulation and probably less water.